The United States and other countries are facing an ever increasing spiral of demands for electric power. Coal powered electric power generation facilities, while relatively cost-effective, nevertheless present a number of adverse environmental issues from an air and water standpoint as well as from a mining standpoint. Nuclear powered electric power generation facilities, while capable of producing significant amounts of electric power, are extremely expensive to build and to operate and represent, to many communities, the ever present danger of a Three Mile Island/Chernobyl type nuclear catastrophe with all of its associated environmental hazards and life-threatening situations. Solar power electric generation facilities, while promising from an environmental impact standpoint, are unlikely to be able to generate significant portions of the vast amounts of power needed presently and in the future given the current state of this particular technology. Hydropower generation offers one of the more promising power generation opportunities through its use of a renewable resource. However, current hydropower generation techniques involve: the expenditure of vast amounts of capital to construct large dams; the flooding and rendering unusable of large areas of land to contain the vast amounts of water required for this type of power generation. In addition, insufficient water depth, water volume, and speed of water flow are factors that significantly limit the areas in which current hydropower generation can be employed. With these limitations in mind, there are numerous areas of the country and of the world that have water resources that could be used to generate hydropower in large amounts if these impediments could be overcome.
One method of overcoming these impediments is to pump water from low areas to higher areas of elevation to allow water to be concentrated in a series of relatively small reservoirs and to allow the energy of falling water to be harnessed for hydropower generation purposes. This type of system would be particularly advantageous for providing peak shaving of electrical loads. A significant volume of water would need to be moved uphill for this objective to be accomplished. Clearly, there is an acute need for the development of a more effective and energy efficient pumping apparatus that will support employment of hydropower generation facilities in areas previously considered not viable for this type of effort.
Rotary or screw pumps have long been the subject of various inventions. For example U.S. Pat. No. Re 29,626 was issued to Allen for a positive displacement rotary pump and drive coupling therefor. The pump was comprised of a progressing cavity, positive displacement rotary pump assembly for fluid or semi-fluid material. The assembly included a rotary shaft with an associated drive motor and pump components including a tubular stator with interior helical surface and an orbital rotor within the stator operably connected to the shaft and having an exterior helical surface. The rotor was coupled to the shaft by a flexible torque tube with one end connected to the shaft by a flexible torque tube and the other connected to an end of the rotor to transmit driving torque to the rotor. However, there was no multiplication of the velocity of the water since the frequency of the blades remained constant throughout the length of the containment tube.
U.S. Pat. No. 4,857,046 was issued to Stevens et al. for a drive catheter having helical pump drive shaft. The catheter included an outer sheath and a rotatable core coupled to a distal tip that directly contacted deposits on the inside of blood vessel inner walls. An outer surface of the rotatable core defined a screw pump for moving dislodged deposits away from the blood vessel through the catheter sheath to a bifurcating adapter located outside the patient. However, there was no multiplication of the velocity of the fluid since the frequency of the blades remained constant throughout the length of the containment tube.
U.S. Pat. No. 5,923,376 was issued to Wright for a Moineau pump with rotating closed end outer member and nonrotating hollow inner member. The pump consisted of a progressive cavity pump with a helical gear pair, wherein the closed end outer gear rotated and orbited relative to a nonrotating hollow inner gear. A hollow inner gear comprising an internal chamber extending axially allowed the flow of pumpable material from progressing cavities to the closed end and through the hollow inner gear. The pump could be used within a material containment vessel, and the invention could be positioned to avoid contact of the pumpable material with any rotating couplings. However, as with the inventions discussed above, there was no multiplication of the velocity of the fluid since the frequency of the blades remained constant throughout the length of the containment tube
U.S. Pat. No. 5,674,063 was issued to Ozaki et al for a screw fluid machine and screw gear used in the same. The screw fluid machine consisted of male and female rotors which were engaged with each other, a casing for accommodating both rotors, fluid working rooms formed by the rotors and the casing, and fluid inlet and outlet ports which were provided in the casing so as to intercommunicate with one end portion and the other portion of the working rooms. The helix angle of the screw gear constituting each of the male and female rotors was set to be continuously varied in a helix advance direction. Although this arrangement did pump fluid there was no multiplication of the velocity of the fluid since the frequency of the helix remained constant throughout the length of the casing.
U.S. Pat. No. 5,961,212 was issued to Haegeman for a screw with continuous and discontinuous blades for water processing apparatus. The apparatus comprised a power source driving a shaft supporting a helicoidal, spiral-shaped screw having an upper end part and fitted round at least part of the shaft, such that water was sucked up or impelled downwards, the screw comprising at least one continuous screw blade and at least one discontinuous screw blade near at least one of its end parts. Although the blades were a combination of continuous and discontinuous construction, there was no multiplication of the velocity of the fluid since the frequency of the two blades remained constant throughout the length of the apparatus.
While these various systems represent inventive approaches to the pumping of fluids, they do not overcome the limitations and impediments currently found in hydropower generation efforts, namely: the requirement for expenditure of vast amounts of capital to construct large dams; the flooding and rendering unusable of large areas of land to contain the vast amounts of water required for this type of power generation; and the restriction of power generation facilities to those areas having sufficient water depth, water volume, and speed of water flow to support hydropower generation using currently available technologies.
Pumping systems capable of overcoming these limitations and allowing hydropower generation at a lower cost of facilities construction, with less loss of land due to the flooding required, and able to operate in areas previously considered unsuitable for hydropower generation due to insufficient water depth, insufficient water volume, and/or insufficient speed of water flow have been disclosed by the present inventor in U.S. Application No. Ser. 10/056,869 and U.S. Pat. No. 6,357,998, both of which are incorporated herein by reference.
The present invention provides additional pumping utility to these ribbon drive pumps by providing additional fluid inlets located in the containment tube or a hollow drive shaft at low pressure regions so as to allow for minimizing cavitation, increasing throughput, and/or mixing of another fluid or fluids with the primary fluid being pumped.